31 lines
1 KiB
Haskell
31 lines
1 KiB
Haskell
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module DotPlugin (transform) where
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import Text.Pandoc
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import Text.Pandoc.Shared
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import System.Process (readProcess)
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import Data.Char (ord)
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-- from the utf8-string package on HackageDB:
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import Data.ByteString.Lazy.UTF8 (fromString)
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-- from the SHA package on HackageDB:
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import Data.Digest.Pure.SHA
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-- This plugin allows you to include a graphviz "dot" diagram
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-- in a document like this:
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--
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-- ~~~ {.dot name="diagram1"}
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-- digraph G {Hello->World}
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-- ~~~
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transform :: Block -> IO Block
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transform (CodeBlock (id, classes, namevals) contents) | "dot" `elem` classes = do
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let (name, outfile) = case lookup "name" namevals of
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Just fn -> ([Str fn], fn ++ ".png")
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Nothing -> ([], uniqueName contents ++ ".png")
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result <- readProcess "dot" ["-Tpng"] contents
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writeFile outfile result
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return $ Para [Image name (outfile, "")]
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transform x = return x
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-- | Generate a unique filename given the file's contents.
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uniqueName :: String -> String
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uniqueName = showDigest . sha1 . fromString
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